Cell module, ozone generator thereof and methods for generating ozone using the same

ABSTRACT

A cell module includes an anode, a cathode and a proton exchange membrane. The anode adheres to one side of the proton exchange membrane while the cathode adheres to the opposite side thereof. The anode comprises a substrate and at least one diamond-like carbon layer covering the substrate. The present disclosure further provides an ozone generator and a method using the same.

BACKGROUND

1. Technical Field

The present disclosure relates to a cell module; in particular, the cellmodule utilizes a diamond-like carbon anode in an ozone generator toproduce ozone.

2. Description of Related Art

The conventional way to sanitize an object is by boiling the object inthe water to destroy the bacteria. Another commonly used way is addingsanitizer, which comprises chlorides or the like, in the washing water.Due to extensive pollution, the number of microorganisms in the tapwater has increased every year so the concentration of chlorides in thesanitizer increases altogether. High concentration chlorides cause apeculiar odor and may result in secondary pollution to the environmentlike detergent does.

Like chlorides, fluorides and ozone are strong oxidants which are proneto gain electrons. However, fluorides are highly toxic to human, thuscannot be used in the drinking or washing water. In the contrary, ozoneis less toxic compared to fluorides meanwhile a potent oxidizing agent,which is 3000 times more effective than chlorides, and therefore in thewater ozone can significantly reduce the bacterial number and decomposechemical remains. The ozone not reacted will automatically decompose tooxygen without secondary contamination to the environment.

Nevertheless, ozone production is a costly process which prevents thepublic implementation of ozone. The conventional ozone generators areultraviolet (UV) light ozone generator, corona discharge method andelectrolysis of water. The UV light ozone generator employs a lampemitting UV light at approximately 185 nanometers (nm) to energizeoxygen molecules (O₂). The energized, highly reactive oxygen freeradicals combine with other oxygen molecules to form ozone (O₃). Howeverthe ozone concentration produced is usually low and higher wavelength UVlight tends to decay ozone.

The corona discharge method uses high voltage currents to ionize gasoxygen and form ozone molecules, which is in relation to the UV lightozone generator. The corona discharge method requires considerablepreparation in advance because the yield of ozone is in directlyproportional to the air dryness and oxygen concentration. In moist air,yields of oxides and other particles increase, which are not easy toseparate from ozone. The high voltage current is mostly converted toheat in the process so cooling devices are essential. Therefore theentry requirement of corona discharge method is high because of the needof complex instrument and regular maintenance.

The conventional electrolysis of water for ozone is by adding water toappropriate electrolytes and supplying DC power to the device. Themetallic electrodes are easily corroded because in the production ofozone many highly reactive molecules are formed as well, thus quickeningthe electrodes decaying. One way is to replace the metallic electrodesby conductive diamond which is hard, resistant to corrosion andchemically inert yet the cost is considerably high so that diamondelectrodes are not widely, commercially implemented.

SUMMARY

The object of the present disclosure is to provide a cell module with adiamond-like carbon electrode and ozone generator using the same, whichis highly efficient, low in cost and having physical properties inaccordance with diamond.

One aspect of the present disclosure is to provide a cell module, whichincludes a proton exchange membrane (PEM), an anode and a correspondingcathode. The anode comprises a substrate and at least one diamond-likecarbon (DLC) layer formed on the substrate. The DLC layer is doped withnitrogen to form the nitride diamond-like carbon (DLC/N). The anodeadheres to one side of lateral faces of the PEM and the cathode adheresto the other thereof.

Another aspect of the present disclosure is to provide an ozonegenerator, which includes a tank, a cell module disposed in the tank andat least two conduction plates. The tank has a plurality of water inletsand a plurality of water outlets. The cell module has a proton exchangemembrane, an anode and a corresponding cathode. The anode comprises asubstrate and at least one diamond-like carbon (DLC) layer formed on thesubstrate. The anode adheres to one side of lateral faces of the PEM andthe cathode adheres to the other thereof. The cell module is flanked bythe two conduction plates at either side respectively.

Still another aspect of the present disclosure is to provide a methodfor ozone production.

In summary, the anode covered by the DLC layer, which is highlyconductive and inexpensive, requires lower voltage current and lesspower, thus significantly reducing energy consumption. The cell moduleis also suitable for long period operation because of the stabilitycontributed by the DLC layer. Additionally, the cell module hassimplified layout with high sterilizing rate.

In order to further understand the present disclosure, the followingembodiments are provided along with illustrations to facilitate theappreciation of the present disclosure; however, the appended drawingsare merely provided for reference and illustration, without anyintention to be used for limiting present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an embodiment of a cell module inaccordance with the present disclosure.

FIG. 2 is an electronic microscope diagram of a diamond-like layer on asubstrate in accordance with the present disclosure.

FIG. 3 is a schematic diagram of an embodiment of an ozone generator inaccordance with the present disclosure.

FIG. 4 is a graph showing a relationship between the current (A) andpotential (V) of nitride diamond-like carbon and platinum.

FIG. 5 is a graph showing ozone concentration (ppm) versus time (min) ofa first embodiment in accordance with the present disclosure.

FIG. 6 is a graph showing E. coli cell count (%) versus time (min) of afirst embodiment in accordance with the present disclosure.

FIG. 7 is a graph showing a relationship between the redox potential(mV) and time (min) of a second embodiment in accordance with thepresent disclosure.

FIG. 8 is a graph showing a relationship between the redox potential(mV) and time (min) of a third embodiment in accordance with the presentdisclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The aforementioned illustrations and following detailed descriptions areexemplary for the purpose of further explaining the scope of the presentdisclosure. Other objectives and advantages related to the presentdisclosure will be illustrated in the subsequent descriptions andappended drawings.

FIG. 1 shows an embodiment of a cell module 10 in accordance with theinstant disclosure. The cell module 10 includes an anode 11, cathode 12and a proton exchanger membrane (PEM) 13. The anode 11 has a substrate111 and at least one diamond-like carbon layer (DLC) 112 formed on thesubstrate. The cathode 12 connects to the other side of the PEM 13opposite to the anode 11. The anode 11 adheres to one side of lateralfaces of the PEM 13 and the cathode 12 adheres to the other thereof.

The substrate 111 is made from carbon cloth, carbon paper, other carbonmaterials and the combination thereof. At least one DLC layer 112 isformed on the surface of substrate 111 by chemical vapor deposition(CVD). The substrate 111 and DLC layer 112 together form the anode 11.In this embodiment, the substrate 111 is made from carbon paper. Asshown in FIG. 2 a, the carbon paper of the substrate 111 is constructedby alternatively woven carbon fabric. In addition, as shown in FIG. 2 b,the substrate 111 is completely covered by the DLC layer 112 after CVD.The preferred thickness of the DLC layer 112 ranges from 2 to 1000 μm.Furthermore, the properties of the DLC layer 112 can be modified byadding trace of different dopants; for example, to increase theconductivity of the anode 11, boron and nitrogen are used. When hydrogenand fluoride are doped, the DLC layer 112 becomes more hydrophobic. Themass percentage of the dopant is preferably between 10 to 30 percentagesof the DLC layer 112 mass.

The cathode 12 is made of conductive materials, selected from platinum(Pt), copper (Cu), silicon dioxide (SiO₂), carbon dioxide (CO₂), carboncloth, carbon paper, carbon materials and the combination thereof. Inthis embodiment, the cathode 12 is made from carbon paper. The size ofthe anode and cathode is about 3 by 3 cm². The PEM 13 is made of Nafion,which is a sulfonated tetrafluoroethylene based synthetic polymer. Thepreferred thickness of the PEM 13 ranges from 2 to 1000 μm. The cellmodule 10 is assembled by hot pressing (temperature: 130° C.) the anode11 and cathode 12 to tightly adhere on either side of the PEM 13separately and using CVD to accumulate DLC layer 112 over the anode 11.

The present disclosure also provides an ozone generator 1 based on theaforementioned cell module 10. The ozone generator 1 includes the cellmodule 10, a tank unit 20 and at least two conduction plates 30. Thetank unit 20 has a plurality of water inlet 23 and a plurality of wateroutlet 24. The ozone module 10 is fixed and flanked by the conductionplates 30 over anode 11 and cathode 12 respectively.

FIG. 3 shows an embodiment of the ozone generator in accordance with thepresent disclosure. The tank unit 20 is made of anti-oxidized materials;for example, poly(methyl methacrylate) (PMMA). The tank unit 20 includesa anode water tank 21 and a cathode water tank 22. The first and cathodewater tank 21, 22 have a plurality of corresponding fastening holesrespectively (not shown in the diagram). The water inlets 23 arearranged on one side of the first and cathode water tank 21, 22 over thelower halves thereof. On the other hand, the water outlets 24 arearranged opposite to the water inlets 23 over the same side of the firstand cathode water tank 21, 22.

The conduction plates 30 are made of metallic materials; for example,stainless steel and aluminum. The conduction plates 30 have a frameportion 31 and a connection portion 32 extending from the frame portion31. In this embodiment, the frame portion 31 is a rectangle slab.Suitable material for the frame portion 31 includes stainless steel andaluminum. The connection portion 32 is preferably a rod made of the samematerial. The detail regarding the cell module 10 can be referred to theforegoing description.

The ozone generator 1 is assembled in the following order in a stackedconfiguration: the anode water tank 21, one of the conduction plates 30,the cell module 10, another one of the conduction plates 30 and thecathode water tank 22. After the initial assembly, the first and cathodewater tank 21, 22 are bolted together via the corresponding fasteningholes. Inside the tank unit 20 the cell module 10 is sandwiched betweenthe conduction plates 30. In other words, the frame portion 31 of one ofthe conduction plates 30 contacts the DLC layer 112 of the anode 11; theframe portion 31 of another one of the conduction plates 30 contacts thecathode. The connection portion 32 of the conduction plates 30 protrudesout of the tank unit 20, and is configured to establish electricalconnection from a power source to the ozone generator 1.

The present disclosure further provides a method for ozone production bythe aforementioned ozone generator 1, which includes steps of adding tapwater to the tank unit 20 at a rate of 1 L/min via the water inlets 23and supplying DC power to the anode 11 and the cathode 12 through theconnection portion 32 respectively. The preferred voltage level of theDC power ranges between 3 to 15 volts.

FIG. 4 shows a graph of the current versus electrical potential of Ptand the nitride DLC (DLC/N) layer 112. The redox potential of the DLC/Nlayer (2.7V) is higher than the redox potential of Pt (1.7V). A fullreaction potential of electrolysis of water to generate oxygen andhydrogen is 1.23V while a higher potential, 1.51V, is needed to generateoxygen, hydrogen and ozone. Furthermore, a half reaction potential ofthe molecular oxygen reacting with oxygen free radicals to form ozone is2.07V. That is to say Pt can act as an electro-catalyst for electrolysisof water to produce hydrogen and oxygen yet the DLC/N layer can sustainhigher potential to produce hydrogen, oxygen and ozone altogether.

FIG. 5 shows a graph of ozone concentration in the tank unit 20 versustime. As voltage is applied to the cell module 10, ozone and hydrogenions are formed over the anode 11. The generated ozone dissolves in thewater, which can be used for washing purposes, and the hydrogen ionspass through the PEM 13 to the cathode 12 to form hydrogen and completethe full reaction. The ozone concentration may be determined bymeasuring the corresponding redox potential in the tank unit 20.

FIG. 6 shows a graph of E. coli cell count in a solution. The solutionis mixed with the water containing ozone. After 10 minutes, the E. colicell count reduced 15%, showing that the ozone in the water is potent tosterilize in a solution. In addition, using the water containing ozoneto wash vegetables with pesticides can greatly reduce the pesticidesconcentration to a level substantially close to none.

A second embodiment of the present disclosure is shown in FIG. 7, whichis a graph showing redox potential versus time. This embodiment showsozone production rate with different numbers of the DLC/N layer 112. InFIG. 7, a line with square data points has a single layer of the DLC/Nlayer 112 on the substrate 111, a line with round data points has twolayers of the DLC/N layer 112 and a line with triangle data points hassix layers of DLC/N layer 112.

The result shows that when multiple layers of DLC/N layer 112 are formedon the substrate 111, the anode 11 has higher redox potential. Thepreferred number of layers is between 2 to 6 so the ozone generator 1can produce high concentration ozone and prolong the lifespan of anode11 because of the stability of the plurality DLC/N layers 112.

A third embodiment is shown in FIG. 8, which shows a graph of anotherredox potential versus time. In this embodiment, the anode 11 has 6layers of the DLC/N layer 112, but the cell module 10 has differentsizes of reaction area. The reaction area is equivalent to the areacombination of the anode 11 and cathode 12. In FIG. 8, a line joined byround data point represents the reaction area of 64 cm²; a line joinedby square data points represents the reaction area of 9 cm². The resultshows that as the reaction area increases, the redox potential increasesas well. That is to say the ozone concentration produced by the ozonegenerator 1 is in directly proportional to the reaction area.

In summary, the instant disclosure provides the cell module 10 and theozone generator 1 using the same is simple in structure, lower inmanufacturing cost, and stable. The materials used for the ozonegenerator 1 also have the feature of low environmental impact. The anode11 is inexpensive yet having higher conductivity compared to theconventional metallic or conductive boron diamond anodes. The physicalproperties of the DLC layer 112 are in accordance with the diamond,which is resistant to corrosion and strong solutes so to prolong thelifespan of the ozone generator 1. Also, the ozone generator 1 issuitable for long period operation because the voltage and powerrequired thereof are lower. Additionally, the method for ozoneproduction yields higher concentration ozone without toxic sideproducts.

The descriptions illustrated supra set forth simply the preferredembodiments of the present disclosure; however, the characteristics ofthe present disclosure are by no means restricted thereto. All changes,alternations, or modifications conveniently considered by those skilledin the art are deemed to be encompassed within the scope of the presentdisclosure delineated by the following claims.

What is claimed is:
 1. A cell module comprising: a proton exchangemembrane; an anode, including a substrate and at least one diamond-likecarbon layer formed on a surface thereof, adhered to one side of theproton exchange membrane; a cathode, corresponding to the anode, adheredthe opposite side of the proton exchange membrane.
 2. The cell moduleaccording to claim 1, wherein the proton exchange membrane material isformed by a sulfonated tetrafluoroethylene based material.
 3. The cellmodule according to claim 1, wherein the substrate is made of a materialselected from the group consisting of carbon cloth, carbon paper and thecombination thereof, and the anode is made of a material selected fromthe groups consisting of platinum, copper, silicon dioxide, carbondioxide, carbon cloth, carbon paper, carbon materials and thecombination thereof.
 4. The cell module according to claim 1, whereinthe diamond-like carbon layer further comprises a dopant.
 5. The cellmodule according to claim 4, wherein the dopant is nitrogen and the massfraction is between 10 to 30 percentages of the diamond-like carbonlayer.
 6. The cell module according to claim 1, wherein the diamond-likecarbon layer is multi-layered.
 7. The cell module according to claim 1,wherein the diamond-like carbon layer has two to six layers.
 8. An ozonegenerator, including: a tank with a plurality of water inlets and aplurality of water outlets; a cell module disposed in the tank,including a proton exchange membrane, an anode and a correspondingcathode, wherein the anode adheres to one side of the proton exchangemembrane, the anode includes a substrate and at least one diamond-likecarbon layer, the cathode adheres to the other side of the protonexchange membrane, and at least two conduction plates disposed on eitherside of the cell module.
 9. The ozone generator according to claim 8,wherein the diamond-like carbon layer further comprises a dopant. 10.The ozone generator according to claim 8, wherein the dopant is nitrogenand the mass fraction is between 10 to 30 percentages of thediamond-like carbon layer.
 11. The ozone generator according to claim 8,wherein the diamond-like carbon layer is a multi-layered.
 12. The ozonegenerator according to claim 8, wherein the diamond-like carbon layerhas two to six layers.
 13. The ozone generator according to claim 8,wherein the tank is made of anti-oxidized materials and the tankincludes a anode water tank and a cathode water tank, wherein the firstand cathode water tank have a plurality of corresponding fasteningholes.
 14. The ozone generator according to claim 8, wherein theplurality of water inlets open at lower halves on one side of the firstand cathode water tank and the plurality of water outlets open at upperhalves, opposite to the water inlets, of the first and cathode watertank.
 15. The ozone generator according to claim 8, wherein the protonexchange membrane is formed by a material based on sulfonatedtetrafluoroethylene.
 16. The ozone generator according to claim 8,wherein the substrate is made of a material selected from the groupconsisting of carbon cloth, carbon paper and the combination thereof,and the anode is made of a material selected from the groups consistingof platinum, copper, silicon dioxide, carbon dioxide, carbon cloth,carbon paper, carbon materials and the combination thereof.
 17. Theozone generator according to claim 8, wherein each of the conductionplates includes a frame portion and a connection portion formed by anextension from the frame portion.